Coking of agglomerates



Sept. 24, 1935. r.:.v H. BUNCE COKING 0F AGGLOMERATES Filed Oct. 9, 1935ates.

Patented Sept. 234, 1935 PATENT oFFicE 2,015,336 COKING 0F AGGLOMERATESEarlll. Bunce, Palmerton, Pa., assignor to The New Jersey Zinc Company,New York, N. Y., a corporation of New Jersey Application october 9,193s, soi-ini No. 692,770

11 Claims.

'I'his invention relates to the coking of agglomerates containing acoking agent, and has for its object the provision of an improved methodof and apparatus forcoking such agglomerthe coking of agglomerates ofmetalliferous material and an appropriate coking agent; such, -forexample, as agglomerates of mixed zinciferous and carbonaceousmaterials; but it may also be usedwith advantage for cokingfuel'brlquettes or agglomerates containing a suitable proportion of anappropriate coking agent.

The invention contemplates the coking of agn glomeratesby direct contactwith non-oxidizing hot gas, the agglomerates being immediately.subjected to contact with the hot gas after g charging into theapparatus where the coking is carried out. The hot gas used to coke thed .agglomerates is withdrawn without dilution with air or steam, so thatthe heat remaining in the @gas may be efficiently utilized; such as inthe drying of agglomerates about to be coked, tov

'fheat waste heat boilers, or for other useful purposes. The practice ofthe4 present invention isparticularly advantageous for cokingagglomerates that contain only a small percentage of binder, oragglomerates that contain oil or tar as binder, or agglomerates thatcontain a relatively high percentage of -bituminous coal.

In accordance with the present invention, the agglomeraties to be cokedare heated to the required coking temperature by passing a nonoxidizinggaseous heating medium transversely through and in direct contact withan appropriately supported body of agglomerates. In one of its aspects,the invention contemplates the use of an appropriate coking chamber,preferably vertical, through which the body or column of agglomerates isprogressively advanced while non-oxidizing heating gases are passedthrough the body of agglomerates in a direction apcoking zone of thechamber. Furthermore, special means are provided for withdrawingcontinuously by suctionl air that leaks into the discharging opening ofthe coking chamber and leading such air oi separately so that it doesThe invention is particularly useful .for

, chamber I0. This louvre construction minimizes gases from the Meansare likewise provided not mix with the hot exhaust coking chamber.

` for withdrawing separately by suction air that enters the chargingopening of the coking chamber during the charging. These devices render5 it possible t'o secure exhaust gases of high, temperature from thecoking chamber, since they are not diluted with air entering theapparatus through the charging and-discharging openings.

The novel features of the present 4invention 10 will be best understoodfrom the following description, taken in conjunction with theaccompanying drawing, which shows a side elevation of a coking apparatusillustrative of a practice of the invention.

The coking apparatus shown comprises a brickwork structure 5, of ovalhorizontal section, having a gas inlet ue 6 and a gas outlet flue 1.Clean-out openings 20 are provided in the curved ends of the structure5. A relatively narrow coking chamber 8 is built midway between the endsof the structure 5, thereby providing on one side a gas distributingchamber 9 communicating with the inlet 6 and on` the other-side asimilar chamber III communicating with the outlet '1. One side wall I2of the coking chamber is substantially vertical, while the other sidewall I3 is slightly inclined outwardly so that the cross sectional areaof the chamber increases from the top to the bottom. Both side walls ofthe coking chamber are permeable to the passage therethrough of gas inconsiderable volume. This permeability is preferably provided byuniformly distributed openings or slots in each side Wall.

In the coking chamber illustrated, the vertical side wall I2 is built upof superposed tiles or' plates having uniformly distributed slots, Thesetiles may be made of refractory material, such as silicon carbide aloneor mixed with clay, or of temperature-.resistant metal alloys,l such asalloys of iron, chromium and nickel. The inclined wall I3 is built up oflouvres positioned so that the gas streams leaving the coking chamberare directed upwardly into the gas-exiting the possibility of dust andbroken pieces of agglomerates lodging in and choking the openings on thegas-exit side of the coking chamber. If desired, a more detaileddescription of the coking chamber itself may be obtained by referring tomy copendlng application Serial No. 391,825, filed September 11, 1929.Reference may also be made to my copending application Serial No.692,771, filed October 9, 1933, in which the apparatus of this inventionis described. 55

The upper end of the coking chamber I extends through the roof oi' thestructure l to form an extension 36, which should be thoroughlyheatinsulated. This heat insulated extension is joined to the cokingchamber at a point on a line with the lower edge of a roof 68 of thestructure 5. A charging hopper 22 provided with a sliding gate 23 ismounted at one side of the extension 36. The extension 35 is providedwith a by-pass connection to the exhaust gas pipe 5| by a. pipe 24,which is provided with a control damper 31. The pipe 24 may also beclosed by a damper 3|. 'I'he top of the extension 36 is connected to thepipe 30 which discharges into the atmosphere and is placed under suctionby a fan (not shown). The damper 3| is so mounted that it may be placedso as to close the pipe 30 and open the pipe 24; or close the pipe 24and open the pipe 30.

A discharging device consisting of an inclined. chute 25 and a rotatablymounted cylinder 26 is operatively associated with the -lower end of thecoking chamber 8. 'I'he lower end of the chute is closed bya pivotallymounted gate 21 biased to its closed position by a counterweight 26. Apipe 35 provided with a control damper 33 connectsthe lower end of thechute with the pipe 36.

'I'he pipe 1 connects the gas exiting chamber I to a dust catcher 5|).An exhaust gas pipe connects the dust catcher 50 with a waste heatboiler unit 53. As already pointed out hereinabove, the pipe 24 joinsthe upper extension 36 of the coking chamber to the exhaust gas pipe 5|.The pipe 24 is provided with an air inlet 52, provided with appropriatemeans for regulation, at a point near the junction of pipe 24 and 5|.

'I'he Waste heat boiler unit 53 is connected by a flue 54 to a hot fan56 and through flue 51 provided with damper 55 to a stack 51-A. A branchflue 58 joins the ilue 51 at a point between the damper 55 and the fan56. The branch iiue 58 is likewise provided with a control damper 59.The flue 58 is connected with a manifold 60 equipped with controldampers 6|. The manifold 6D discharges into the top of a briquette drier62, equipped with a traveling, grate 63, of any appropriate conventionaltype, adapted for the support of a charge of briquettes. The briquettedrier 62 is provided with an exhaust flue 64, operatively connected withanexhaust fan' 65. i

When the apparatus is in operation, the coking chamber 8 and part oftheupper extension 36 are filled with agglomerates undergoing coking.The heating gas for coking is introduced through the gas inlet 6, bymeans of suction applied by fan 56 to the gas outlet 1. Any appropriatesource of heating gas (inert to the charge under the conditions ofcoking) may beused.v Thus the heating gases may be producer gas andsimilar fuel gases extraneously heated when necessary. The combustiongases provided by the burning of fuel gases may also be used; forexample, the exhaust gases i'romv a combustion chamber used to heatretorts in which the coked charge of agglomerates of a coking agent andzinciferous material coked in the coking chamber 8 are subsequentlyreduced, may be utilized to carry out the coking. The'gas used forcoking should not contain constituents capable of oxidizing anyappreciable amount of the charge in the coking chamber 8.

The heating gas enters the chamber 8 and is distributed through theopenings of the vertical wall I2 into the coking chamber 8. The gas -andopen the pipe 30.

verted into the upper charging extension 36, or

hot top, may be regulated by adjusting the, damper 31. The briquettesentering the upper extension 35 of the coking chamber 8 are thusinstantaneously exposed to the heat of the hot gases and are broughtwith rapidity to the coking temperature; in accordance with the methodof my above-mentioned copending application Serial No. 391,825.

The charging of raw agglomerates and the discharging of cokedagglomerates are, preferably,

carried out simultaneously. During these operations the swinging gate2.3 of the charging hopper 22 is opened for the insertion of rawagglomerates and the gate 21 opened for the discharge of cokedagglomerates, the discharge of which is facilitated by rotating thecylinder 26. On opening the swinging gate 23 and the gate 21, the damper3| is placed so as to close the pipe 24 The suction in the pipe 3|)withdraws and discharges to the atmosphere 30 any air that may enterthrough the open gate 23. Likewise the suction created in the pipe drawsany air that may enter the discharge chute from the open gate 21 up intopipe 35, thence into pipe 30 and out to the atmosphere. 3 Further, anyleakage of air by gate 21 when closed is continuously drawn through pipeinto pipe 30 and out to the atmosphere. In this way any false air thatmay enter the system through these gates is removed so that it cannotenter the coking chamber 8' and oxidize the agglomerates undergoingcoking, and likewise does not dilute the hot exhaust gases withdrawn bysuction through the pipe 1, or burn the volatile matter in these gases.

When the charging and discharging operations o are completed thegates.23 and 21 are closed and the damper 3| then placed so as to closethe pipe 3|! and open the pipe 24. The upper extension 36 of the cokingchamber 8 then stands under 50 suction produced in the pipe 24 onaccount of its connection with the exhaust gas pipe 5 I, which itself isunder suction produced by the fanA 56. The pipe 35 is continually undersuction on account of the fact that it is connected to pipe 30. 5 Thesuction produced at the discharge opening by the pipe 35 tends towithdraw from the coking system and discharge to the atmosphere any airthat may leak in while the gate 21 is closed.

The suction produced in the pipe 35 may be conw to be suflicient to burnthe combustible constituents of the exhaust gases is drawn in Ithroughthe air inlet 52. From the pipe 5|, the exhaust gases enter thewaste-heat boiler unit 5,3,4 where their palpable heat, and the heat ofcombustion of the combustible constituents that they contain,

are in part recovered and utilized to generate steam.

The exhaust gases leave the waste heat boiler unit through the flue Iand fan 56 intoilue 51. From flue 51 two means of escape for the exhaustgases are provided. The exhaust gases may pass either (a) directlythrough the flue 51 to the stack 51-A, or (b) through the branch ue 58to the manifold 60 discharging into the briquette drier 62, whence theexhaust gases pass to the fan 65 through the flue 64. The exhaust gasesmay be distributed as desired between these two routes by appropriateregulation and adjustment of the control damper 55 (regulating theamount of exhaust gases going to thestack 51A) and of the control damper59 (regulating theamount of gases entering the flue 5B and the briquettedrier 62)'.

In actual operation the suction draft required for the appropriateoperation of the cokingl unit is4 provided by the fan 56. The dampers 59and 55 are preferably so set that sufiicient hot exhaust gases are drawnthrough the briquette drier 62 to dry the briquettes therein to thedesired extent priorto charging them into the coking chamber. 8. Thus,if it should develop at any time that the volume of exhaust gases goingto the briquette drier 62 is toohigh for appropriate drying, the amountof exhaustgases entering the briquette drier can be checked by partiallyclosing the control damper 59. A uniform pressure may be maintainedl onthe system by opening the control damper 55, releasing more exhaustgases to the stack 51-A. If it should develop at any time that thetemperature of the briquette drier 62 is too high for appropriatedrying; cold diluting air may be introduced under pressure in regulatedamounts to ilue 58.

' The vcontrol dampers 6I, utilized ordinarily to regulate thedistribution of the exhaust gases in the manifold 60 discharging intothe briquette drier 62, may likewise be utilized to check the totalamount of hot gases entering the briquette drier from the manifold, ifdesired.

The coking apparatus of the present inventhenature and kind of binderand the amount of bituminous coal present. Briquettes containing as muchas 5% moisture have been satisfactorily coked in the apparatus of theinvention, and in some cases mere skin drying is suflicient. Thebriquettes may be dried by exposing them to the exhaust gases exitingfrom the pipe 51, after a large part of the heat in these gases has beenrecuperated by waste heat boilers, forexample, as described hereinbeforeor by other means. Where the heat in the exhaust gases from the cokingchamber is recuperated by waste heat boilers, it

is desirable from the standpoint of elcient heat recoveryto dry thebriquettes down to a moisture content of 1 to 2% before charging theminto the coking chamber, since it is better to drive off the bulk of themoisture in the briquettes with the low temperature gases exiting fromthe waste heat boilers than with the. high temperature gas in thecokingchamber.

3 The exclusion of air from the coking system by the application ofsuction to the charging and discharging openings of the coking chamberprevents the combustion in the coking chamber of the fuel gasesgenerated therein during the cok- 5 ing of the charge. These fuel gasesthus escape from the coking chamber along with the exhaust gases. Wherewaste heat boilers are employed to. recover the heat from the exhaustgases, it is desirable to burn these fuel gases near the boilers inorder to recover their heat of combustion. This may be effected bydrawing regulated amounts of air into the system at the entrance to thewaste heat boilers, so as to burn any combustible material in theexhaust gases at this point. In the practice of the present invention itis possible to coke agglomerates of the character mentioned in such away as to make them substantially uniform in quality. This result isobtained because each agglomerate may be subjected to substantially thesame type of heat treatment. To this end a shallow bodyof theagglomerates is preferably subjected to the heat treatment operation.Large volumes of hot gases are passed through the body of agglomeratesand k in contact with them. In a preferred practice of the invention, inthe case of agglomerates containing zinciferous material, the heatinggas enters the body of agglomerates at a temperature materials, thathave unusual'strength; and that may be subjected to an appropriatereduction operation in, auch a, manner that the resulting residues arestill in the formof agglomerates having substantially the same size andshape as originally. This desirable result is in large part obtainedwhen the fresh or green agglomerates introduced into the coking chamberhave suflcient initial strength to withstand the compression andabrasion to which they are subjected in their passage to and into thechamber. To this end, the agglomerates-after they are formed, are y'dried out orbaked with the relatively hot gas withdrawn from the cokingoperation, which serves to give them the initial strength required.

The factors tending to disrupt an agglomerate during coking are thesteam generated within the agglomerate, due to moisture, and thevolatile matter liberated by the bituminous and other an carbonaceousmaterial.

By drying before coking, moisture is driven off theagglomerate thatotherwise would be driven off during the coking operation tending todis- Therefore, drying makes rupt the agglomerate. it possibletoincrease the amountI of volatile matter that may be liberated withinthe briquette without disrupting it, thereby permitting a greaterpercentage of coking material in thegreen agglomerate, resulting inincreased strength in the final coked agglomerate and a decidedlyincreased strength in the residue resulting from an appropriate reducingoperation.

I claim;

1. In the method of coking briquets-containing a coking agent by passinghot substantially nonoxldizing gases transversely through a column ofbriquets in a vertical coking chamber provided with a heat insulatedcharging extension at the top, the improvement which comprisesmaintaining the said charging extension hot by diverting hot gasesupwards therethrough by applying suction thereto and subjecting briquetsintroduced into said heat insulated charging extension to sudden heatwith said diverted hot gases.

2. In the method of coking agglomerates of mixed zinciferous andcarbonaceous materials containing a coking agent by passing hotsubstantially non-oxidizing gas transversely through a column of theagglomerates in a vertical coking chamber charged at the top anddischarged at the bottom, the improvement which comprises protecting theagglomerates from oxidation during the coking and at the same timeavoiding loss of heat by dilution of the said hot gas with air bysubjecting the lower end of the column of agglomerates to suction andwithdrawing air leaking into the discharge opening separately from themain current of hot gas leaving the column of agglomerates.

3. In the method of coking agglomerates of mixed zinciferous andcarbonaceous materials containing a coking agent by passing hotsubstantially non-oxidizing gas transversely through a column of theagglomerates in a verticalcoking chamber charged at the top anddischarged at the bottom, the improvement which comprises protecting theagglomerates from oxidation during coking and at the same time avoidingloss of heat by dilution of the said hot gas with air by subjecting theupper end of the column of agglomerates to suction during the chargingof said vertical coking chamber, and withdrawing air entering thecharging opening and steam evolved from the freshly charged agglomeratesseparately from the main current of hot gas leaving the coking chamberwhile the charging opening of the coking chamber is open.

4. In a method of coking agglomerates of mixed zinciferous andcarbonaceous materials containing a coking agent by passing hotsubstantially non-oxidizing gas transversely through a column of theagglomerates in a vertical coking chamber charged at the top anddischarged at the bottom, the improvement which comprises protecting theagglomerates from oxidation during coking and at the same time avoidingloss of heat by dilution of the said hot gas with air, by subjecting theupper end of the column of agglomerates to suction during the chargingof said vertical coking chamber, withdrawingv air entering the chargingopening and steam evolved from the freshly charged agglomeratesseparately from the main current of hot gas leaving the coking chamberwhile the charging opening of the coking chamber is open, then afterclosing the charging opening of the coking chamber withdrawing gas bysuction from the top of the column of agglomerates, subjecting the topof the agglomerate col. umn to sudden heating by hot gases divertedupwards from said coking chamber by said suction, and returning the gasso withdrawn to the main current of hot gas leaving the coking chamber.

5. In a method in which agglomerates of zinciferous material,carbonaceous material and a coking agent are coked in a column which isheated by a current of hot substantially non-oxidining gas passingtransversely through said column, fresh agglomerates beingvsupplied atone end of the column and coked agglomerates being withdrawn from theother end of the column, the improvement which comprises preventing theloss of heat in the end of the column to which the agglomerates aresupplied and diverting a substantial portion of the transverse gascurrent into 5 this end of the column so that said fresh agglomeratesare rapidly brought to their coking temperature.

6. In a method of coking agglomerates of mixed zinciferous andcarbonaceous materials containing a coking agent, the improvement whichcomprises introducing a charge of fresh agglomerates into the top of avertically disposed coking chamber in which the charge is heated by atransverse current of hot substantially non-oxidizing gas, separatelywithdrawing from the top of said coking chamber air which enters thecoking chamber with the charge and steam liberated from thecharge'immediately after its introduction into the coking chamber,diverting a portion 20 of the transverse current of heating gas into thetop of the chamber after the air and steam have been removed to bringthe agglomerates rapidly to the coking temperature, and returning thediverted portion of the gas current undiluted by 25 air into the main-gas current at a point beyond -the exit of the gas currents from thecoking chamber.

'1. In a method of coking agglomerates of mixed zinciferous andcarbonaceous materials in a vertically disposed coking chamber heated bya current of hot substantially non-oxidizing gas passingtransverseltherethrough, the improvement which comprises withdrawingseparately by suction air which enters the coking chamber with freshagglomerates, diverting a portion of the transverse gas stream into thatportion of the coking chamber in which fresh agglomerates are introducedafter the air has been withdrawn in order to bring the agglomeratesrapidly to the 40 coking temperature, and returning the diverted portionof the gas current undiluted by air into the main gas current at a pointbeyond the exit of the gas currents fro'm the coking chamber.

8. In a method of coking agglomerates of mixed 45 zinciferous andcarbonaceous materialsk in a vertically disposed coking chamber heatedby a current of subustantially non-oxidizing gas passing transverselytherethrough, fresh agglomerates being supplied to the coking chambernear the top and coked agglomerates being withdrawn near the bottom ofthe coking chamber, the improvement which comprises withdrawingsepavrately by suction 'air which enters the coking chamber at a pointnear which the coked agglomerates are discharged so that the gas streamis not diluted by said air.

9. In a method of conserving heat for utilization in a waste heat boileroperatively associated with a vertical coking chamber into the top ofwhich agglomerates of mixed zinciferous and carbonaceous materialscontaining a coking agent are charged and coked by passing hotsubstantially non-oxidizing gas transversely through a column of theagglomerates within the vertical coking chamber, the coked agglomeratesbeing withdrawn from a discharge opening at the bottom of the verticalcoking chamber, the improvement which comprises protecting the agglomer70 ates from oxidation during the coking and at the same time avoidingloss of heat by dilution of the said hot gas with air by subjecting thelower end of the column of agglomerates to suction, and withdrawing airleaking into the discharge open- 75 aolassc passing hot substantiallynon-oxidizing gas transversely through a column of the agglomerateswithin the vertical coking chamber, the coking` chamber being charged atthe top and discharged at 'the bottom through gates. the improvementwhich comprises protecting the agglomerates from oxidation during cokingand at the same time4 avoiding loss of heat by dilution of the said hotgas with air by subjecting the upper end of the column to suction duringthe charging oi' said vertical coking chamber, and withdrawing airentering the charging gate and steam evolved, from the freshly chargedvagglomerates separately from the main current of hot gas leaving thecok- .ing chamber while the charging gate oi' the coking chamber isopen.

11. In a method ofconserving heat for utilization in a waste heat boileroperatively associated with a vertical coking chamber whereinagglomerates ofA zincii'erous and carbonaceous materials containing a`coking agent' are coked by passing hot substantially non-oxidizing gastransversely through a column oi' the agglomerates in the verticalcoking chamber which is charged at the top and discharged at the bottomthrough gates. the improvement which comprises protecting theagglomerates from oxidation during coking and at the same time avoidingloss of heat by dilution of the said hot gas with air by subjecting 10the upper end of the column of agglomerates to suction during thecharging oi' said vertical coking chamber, withdrawing air entering thecharging opening and steam evolved from the freshly charged agglomeratesseparately from the main current of hot gas leaving the coking chamberwhile the charging gate of the coking chamber is open, then afterclosing the charging gate of the lcoking chamber withdrawing gas bysuction from the top of the column of agglomerates, subjecting m the topof the briquet column to sudden heating by hot gases diverted upwardsfrom said coking chamber by said suction, and returning the gas 'sowithdrawn to the main current of hot gas leaving the coking chamber.

EARL H. BUNCE.

